/**
     * @license
     * Copyright 2016 Google LLC
     * SPDX-License-Identifier: Apache-2.0
     */

/**
 * @fileoverview Helper functions for generating Lua for blocks.
 * Based on Ellen Spertus's blocky-lua project.
 * @suppress {checkTypes|globalThis}
 */

import * as Blockly from 'blockly/core';
import { Names } from '../others/names';

/**
 * Order of operation ENUMs.
 * http://www.lua.org/manual/5.3/manual.html#3.4.8
 * @enum {number}
 */
const Order = {
    ATOMIC: 0,    // literals
    // The next level was not explicit in documentation and inferred by Ellen.
    HIGH: 1,            // Function calls, tables[]
    EXPONENTIATION: 2,  // ^
    UNARY: 3,           // not # - ~
    MULTIPLICATIVE: 4,  // * / %
    ADDITIVE: 5,        // + -
    CONCATENATION: 6,   // ..
    RELATIONAL: 7,      // < > <=  >= ~= ==
    AND: 8,             // and
    OR: 9,              // or
    ASSIGNMENT: 14,     // = *= /= ~/= %= += -= <<= >>= &= ^= |=
    NONE: 99,
};

/**
 * Lua code generator class.
 *
 * Note: Lua is not supporting zero-indexing since the language itself is
 * one-indexed, so the generator does not repoct the oneBasedIndex configuration
 * option used for lists and text.
 */
export class LuaGenerator extends Blockly.Generator {
    constructor(name) {
        super(name ?? 'Lua');
        this.isInitialized = false;
        this.PASS = '';
        // Copy Order values onto instance for backwards compatibility
        // while ensuring they are not part of the publically-advertised
        // API.
        //
        // TODO(#7085): deprecate these in due course.  (Could initially
        // replace data properties with get accessors that call
        // deprecate.warn().)
        for (const key in Order) {
            this['ORDER_' + key] = Order[key];
        }

        // List of illegal variable names.  This is not intended to be a
        // security feature.  Blockly is 100% client-side, so bypassing
        // this list is trivial.  This is intended to prevent users from
        // accidentally clobbering a built-in object or function.
        this.addReservedWords(
            // Special character
            '_,' +
            // From theoriginalbit's script:
            // https://github.com/espertus/blockly-lua/issues/6
            '__inext,assert,bit,colors,colours,coroutine,disk,dofile,error,fs,' +
            'fetfenv,getmetatable,gps,help,io,ipairs,keys,loadfile,loadstring,math,' +
            'native,next,os,paintutils,pairs,parallel,pcall,peripheral,print,' +
            'printError,rawequal,rawget,rawset,read,rednet,redstone,rs,select,' +
            'setfenv,setmetatable,sleep,string,table,term,textutils,tonumber,' +
            'tostring,turtle,type,unpack,vector,write,xpcall,_VERSION,__indext,' +
            // Not included in the script, probably because it wasn't enabled:
            'HTTP,' +
            // Keywords (http://www.lua.org/pil/1.3.html).
            'and,break,do,else,elseif,end,false,for,function,if,in,local,nil,not,' +
            'or,repeat,return,then,true,until,while,' +
            // Metamethods (http://www.lua.org/manual/5.2/manual.html).
            'add,sub,mul,div,mod,pow,unm,concat,len,eq,lt,le,index,newindex,call,' +
            // Basic functions (http://www.lua.org/manual/5.2/manual.html,
            // section 6.1).
            'assert,collectgarbage,dofile,error,_G,getmetatable,inpairs,load,' +
            'loadfile,next,pairs,pcall,print,rawequal,rawget,rawlen,rawset,select,' +
            'setmetatable,tonumber,tostring,type,_VERSION,xpcall,' +
            // Modules (http://www.lua.org/manual/5.2/manual.html, section 6.3).
            'require,package,string,table,math,bit32,io,file,os,debug'
        );
    }

    /**
     * Initialise the database of variable names.
     * @param {!Workspace} workspace Workspace to generate code from.
     */
    init() {
        // Call Blockly.CodeGenerator's init.
        super.init();
        this.definitions_ = Object.create(null);
        // Create a dictionary of setups to be printed before the code.
        this.functionNames_ = Object.create(null);
        this.setups_ = Object.create(null);
        this.loops_ = Object.create(null);
        this.codeEnd_ = Object.create(null);
        if (!this.variableDB_) {
            this.variableDB_ = new Names(this.RESERVED_WORDS_);
        } else {
            this.variableDB_.reset();
        }
        // this.variableDB_.setVariableMap(workspace.getVariableMap());
        // this.variableDB_.populateVariables(workspace);
        // this.variableDB_.populateProcedures(workspace);

        this.isInitialized = true;
    }

    /**
     * Prepend the generated code with the variable definitions.
     * @param {string} code Generated code.
     * @return {string} Completed code.
     */
    finish(code) {
        // Convert the definitions dictionary into a list.
        if (code !== "") {
            code = code.replace(/\n/g, '\n');
            code = code.replace(/\n\s+$/, '\n');
        }
        var definitions = ['_G.sys = require("sys")'];
        for (let name in this.definitions_) {
            definitions.push(this.definitions_[name]);
        }
        var functions = [];
        for (let name in this.functions_) {
            functions.push(this.functions_[name]);
        }
        var setups = [];
        for (let name in this.setups_) {
            setups.push(this.setups_[name]);
        }
        if (setups.length !== 0)
            setups.push('\n');
        var loops = [];
        for (let name in this.loops_) {
            loops.push(this.loops_[name]);
        }
        var codeEnd = [];
        for (let name in this.codeEnd_) {
            codeEnd.push(this.codeEnd_[name]);
        }
        if (codeEnd.length !== 0) {
            codeEnd.push('\n');
        }
        this.variableDB_.reset();
        if (loops.length > 0) {
            return definitions.join('\n') + '\n'
                + functions.join('\n') + '\n'
                + setups.join('') + '\n' + code
                + 'while true do\n' + loops.join('') + 'end\n'
                + codeEnd.join('\n') + '\nsys.run()';
        }
        return definitions.join('\n') + '\n'
            + functions.join('\n') + '\n'
            + setups.join('') + '\n' + code
            + codeEnd.join('\n') + '\nsys.run()';
    }

    /**
     * Naked values are top-level blocks with outputs that aren't plugged into
     * anything. In Lua, an expression is not a legal statement, so we must assign
     * the value to the (conventionally ignored) _.
     * http://lua-users.org/wiki/ExpressionsAsStatements
     * @param {string} line Line of generated code.
     * @return {string} Legal line of code.
     */
    scrubNakedValue(line) {
        return 'local _ = ' + line + '\n';
    }

    /**
     * Encode a string as a properly escaped Lua string, complete with
     * quotes.
     * @param {string} string Text to encode.
     * @return {string} Lua string.
     * @protected
     */
    quote_(string) {
        string = string.replace(/\\/g, '\\\\')
            .replace(/\n/g, '\\\n')
            .replace(/'/g, '\\\'');
        return '\'' + string + '\'';
    }

    /**
     * Encode a string as a properly escaped multiline Lua string, complete with
     * quotes.
     * @param {string} string Text to encode.
     * @return {string} Lua string.
     * @protected
     */
    multiline_quote_(string) {
        const lines = string.split(/\n/g).map(this.quote_);
        // Join with the following, plus a newline:
        // .. '\n' ..
        return lines.join(' .. \'\\n\' ..\n');
    }

    /**
     * Common tasks for generating Lua from blocks.
     * Handles comments for the specified block and any connected value blocks.
     * Calls any statements following this block.
     * @param {!Block} block The current block.
     * @param {string} code The Lua code created for this block.
     * @param {boolean=} opt_thisOnly True to generate code for only this statement.
     * @return {string} Lua code with comments and subsequent blocks added.
     * @protected
     */
    scrub_(block, code, opt_thisOnly) {
        let commentCode = '';
        // Only collect comments for blocks that aren't inline.
        if (!block.outputConnection || !block.outputConnection.targetConnection) {
            // Collect comment for this block.
            let comment = block.getCommentText();
            if (comment) {
                comment = Blockly.utils.string.wrap(comment, this.COMMENT_WRAP - 3);
                commentCode += this.prefixLines(comment, '-- ') + '\n';
            }
            // Collect comments for all value arguments.
            // Don't collect comments for nested statements.
            for (let i = 0; i < block.inputList.length; i++) {
                if (block.inputList[i].type === Blockly.inputs.inputTypes.VALUE) {
                    const childBlock = block.inputList[i].connection.targetBlock();
                    if (childBlock) {
                        comment = this.allNestedComments(childBlock);
                        if (comment) {
                            commentCode += this.prefixLines(comment, '-- ');
                        }
                    }
                }
            }
        }
        const nextBlock = block.nextConnection && block.nextConnection.targetBlock();
        const nextCode = opt_thisOnly ? '' : this.blockToCode(nextBlock);
        return commentCode + code + nextCode;
    }
}

export const Lua = new LuaGenerator();